Table 3.

Pregnancy outcomes and adjusted odds ratio after stratification analyses based on development stage of vitrified embryos transfer.

	Implantation rate	P-value	aOR (95% CI)	Live birth rate	P-value	aOR (95% CI)
Cleavage embryo (n = 10 630)	4899/17 567 (27.89%)			3065/10 630 (28.83%)
0–2 years	4262/15 663 (27.21%)	ref.		2681/9543 (28.09%)	ref.
2–5 years	558/1654 (33.74%)	0.433	1.06 (0.92–1.22)	334/948 (35.23%)	0.395	0.94 (0.81–1.09)
>5 years	79/250 (31.60%)	0.102	0.74 (0.52–1.06)	50/139 (35.97%)	0.414	0.86 (0.60–1.24)
Extended culture of cleavage embryos (n = 2388)	1252/3871 (32.3%)			802/2388 (33.58%)
0–2 years	814/2757 (29.52%)	ref.		493/1591 (30.99%)	ref.
2–5 years	349/877 (39.79%)	0.538	0.93 (0.74–1.17)	245/617 (39.71%)	0.483	1.08 (0.87–1.35)
>5 years	89/237 (37.55%)	0.650	0.92 (0.65–1.31)	64/180 (35.56%)	0.843	1.04 (0.73–1.48)
Blastocyst (n = 23 414)	14 215/32 977 (43.11%)			9784/23 414 (41.79%)
0–2 years	12 365/28 251 (43.77%)	ref.		8531/20 252 (42.12%)	ref.
2–5 years	1677/4089 (41.01%)	0.088	0.93 (0.85–1.01)	1146/2848 (40.24%)	0.156	0.94 (0.86–1.02)
>5 years	173/464 (37.28%)	0.033	0.78 (0.62–0.98)	107/314 (34.08%)	0.002	0.68 (0.53–0.87)